Formation of piezoelectric devices

Abstract

A method for producing an ultrasonic transducer or an array of ultrasonic transducers, the method comprising: providing or depositing a layer of piezoelectric material on a substrate. The piezoelectric material is a doped, co-deposited or alloyed piezoelectric material. The piezoelectric material comprises: a doped, co-deposited or alloyed metal oxide or metal nitride doped, co-deposited or alloyed with vanadium or a compound thereof; or zinc oxide doped, co-deposited or alloyed with a transition metal or a compound thereof. Optionally, the deposition of the layer of piezoelectric material is achieved by sputter coating, for example using a sputter target comprising the doped or alloyed piezoelectric material. In an example, the layer of piezoelectric material is deposited onto the substrate using high power impulse magnetron sputtering (HIPIMS). A substrate bias (e.g. DC and / or RF) can be used during deposition of the layer of piezoelectric material to obtain further enhancements. In a further example, the substrate is provided on a rotating drum while the layer of piezoelectric material is deposited.

Description

[Technical Field]

[0001] This disclosure relates to the formation of piezoelectric devices such as ultrasonic transducers. [Background Technology]

[0002] Ultrasound spans a frequency range higher than that of human hearing, and typically operates at frequencies greater than 20 kHz. Typical operating ranges extend from 100 kHz to several gigahertz. Due to the much higher frequencies involved, ultrasonic devices are generally quite different from those typically used for audible applications.

[0003] The use of ultrasound in analysis shows great promise in a range of applications, particularly in medical imaging and in fields such as non-destructive testing (NDT), especially in industrial NDT. Dental imaging using ultrasound technology is one example of a suitable application, where ultrasound imaging can be used to determine the properties of tooth layers, such as the enamel, dentin, and pulp, and to determine and characterize the thickness of the layers and any defects, diseases, or other problems within them. However, ultrasound has a wide range of uses, and its applications are not limited to these examples.

[0004] An ultrasonic transducer is operable to generate ultrasonic waves that are transmitted to a sample (e.g., a tooth or a hard material) and to detect the reflection of ultrasonic waves from interfaces between layers of the sample (e.g., the interface between enamel and dentin or between dentin and pulp). By using techniques such as time-of-flight and other analyses, the layers of the sample (e.g., a tooth) can be imaged, thereby characterizing the sample. The application of ultrasound in this application is particularly advantageous because conventional techniques for imaging teeth involve the use of X-rays, which are potentially harmful to both the recipient and the physician administering the radiation and require safe, expensive, and time-consuming control of radioactive materials.

[0005] Conventional ultrasonic transducers are typically formed from bulk ceramic materials, which can be costly, bulky, and difficult to manufacture, especially given the shape and properties desired for many applications. The traditional ceramic materials used in ultrasound are generally not suitable for operation at very high temperatures, making them unsuitable for some applications. In particular, the combination of high-temperature operation and sufficient resolution is problematic for many conventional ultrasonic transducers. Furthermore, conventional ultrasonic transducers are not easily manufactured using automated techniques and often require a high degree of manual operation. Therefore, improved ultrasonic transducers and their manufacturing methods are desired. [Summary of the Invention]

[0006] Various aspects of the invention are defined in the independent claims. Certain preferred features are defined in the dependent claims.

[0007] According to a first aspect of this disclosure, a method for producing piezoelectric devices such as ultrasonic transducers or ultrasonic transducer arrays is provided, the method comprising:

[0008] A piezoelectric material layer is formed or deposited on a substrate.

[0009] The deposition of a piezoelectric material layer can be achieved through sputtering. The piezoelectric material layer can be disposed on or deposited on only one surface of the substrate, such as a flat surface. Alternatively, the piezoelectric material layer can be disposed on or deposited on a portion or all of the surface of the substrate (e.g., a flat surface).

[0010] The piezoelectric material may be or include doped or alloyed piezoelectric materials. Sputtering deposition may include the use of a sputtering target formed of, including, or having the same composition as the piezoelectric material layer in the final piezoelectric device.

[0011] The piezoelectric material and / or sputtering target may be or include a primary piezoelectric material, such as a metal oxide or metal nitride (such as zinc oxide or aluminum nitride) or a doped or alloyed metal oxide or metal nitride. The piezoelectric material and / or sputtering target may include dopants or other materials (such as alloying materials or co-deposited materials), which may be or include transition metals or compounds thereof. For example, the dopant or other material may be vanadium. The dopant or other material may be present in the piezoelectric material and / or sputtering target at a level of up to 10% by weight (e.g., 0.01% w / w to 10% w / w). The primary piezoelectric material, such as a metal oxide or metal nitride, may be present in the piezoelectric material layer at a level of 90% w / w to 99.99% w / w. Dopants or other materials may be integrated, co-deposited, or reacted into the primary piezoelectric material, for example, by forming an alloy with the primary piezoelectric material or by doping into the primary piezoelectric material, and may not be mixed with the primary piezoelectric material or coated onto or within discrete regions of the primary piezoelectric material.

[0012] Methods may include using magnetron sputtering deposition, such as direct current (DC), pulsed DC, radio frequency (RF), closed field magnetron (CFM) sputtering, and / or high power impulse magnetron sputtering (HIPIMS), to deposit piezoelectric coatings. Further enhancements can be obtained using substrate bias (e.g., DC and / or RF), which can optimize the sputtered plasma ion energy during film growth. These specific techniques can provide beneficial film growth morphologies and / or enhanced piezoelectric properties of the piezoelectric layer.

[0013] During the deposition of the piezoelectric material layer, dopants or other materials may be bonded to the primary piezoelectric material, such as a metal, metal oxide, or metal nitride. Dopants or other materials may be bonded to the sputtering target, for example, by doping into the primary piezoelectric material, such as a metal oxide or metal nitride, forming an alloy with it, or by co-deposition from multiple sputtering magnetrons. Dopants or other materials may not be separately coated, adhered to, or deposited onto the primary piezoelectric material in the sputtering target and / or the piezoelectric material layer.

[0014] Dopants or other materials can be co-deposited with the primary piezoelectric material (e.g., a metal, metal oxide, or metal nitride). For example, the dopants or other materials can be provided by a target or sputtering arrangement, and the primary piezoelectric material (e.g., a metal, metal oxide, or metal nitride) can be provided by different targets or sputtering arrangements. Setting up the piezoelectric material layer by co-depositing the primary piezoelectric material and the dopants or other materials allows for easier adjustment or other changes in stoichiometry, for example, during operation.

[0015] The method may include using a drum arrangement to deposit a piezoelectric material layer onto a substrate; for example, the substrate may be positioned on the drum simultaneously with the deposition of the piezoelectric layer onto the substrate. This arrangement can facilitate higher production volumes.

[0016] This allows for the creation of more uniform and / or consistent piezoelectric layers. Furthermore, it enables faster deposition processes and / or the achievement of thicker piezoelectric material layers within a given processing time. Additionally, it reduces the amount of pinholes and other defects.

[0017] The piezoelectric material layer can be a piezoelectric material film, include a piezoelectric material film, or be included in a piezoelectric material film. The piezoelectric material layer can be configured and / or operable to generate ultrasound; that is, the piezoelectric material layer can be or include an ultrasound-generating layer. The piezoelectric material can be or includes an inorganic material. The piezoelectric material can be crystalline, such as a polycrystalline or columnar piezoelectric material. The piezoelectric material layer can be a non-polymeric piezoelectric material layer. The piezoelectric material can be or include a continuous layer of material with piezoelectric properties; for example, the piezoelectric material can be a discrete region of piezoelectric material with piezoelectric properties not included in a non-piezoelectric material matrix. The piezoelectric material layer can have a thickness in the range of 2 μm to 20 μm. The piezoelectric material layer can be thinner than the substrate.

[0018] The method may include providing at least one electrode on a piezoelectric material layer. The method may also include providing multiple electrodes in the form of an electrode array on the piezoelectric material layer. The method may include, for example, providing at least one conductive line and / or at least one electrical connector on the surface of the piezoelectric material or on a resistive layer disposed thereon. The corresponding conductive line can electrically connect the corresponding electrode to the corresponding electrical connector. However, other arrangements for providing and / or electrically connecting the electrodes and / or electrically coupling the piezoelectric material layer may be used.

[0019] An ultrasound device can be an ultrasound device used for imaging, measurement, or testing (e.g., non-destructive testing).

[0020] The method may include providing a second layer. The second layer may include an encapsulating material. The second layer may be or include a dielectric material. The second layer may be or include a polymeric material, such as a dielectric polymer. The second layer may be thinner than the substrate. The thickness of the second layer may be less than 50 μm, for example, between 1 μm and 50 μm. The second layer may include epoxy resin, polyimide, parylene, etc., or be formed therefrom.

[0021] The second layer can be configured to be directly on, above, or covering at least a portion of the surface of the piezoelectric material layer. The second layer can be directly on, above, or covering the side of the piezoelectric material layer opposite to the substrate. The second layer can be directly on, around, and / or between at least some or all of the conductive lines and / or at least one electrode (e.g., electrodes of an electrode array). The second layer can be electrically insulating. The second layer can expose at least some or all of the connector. The second layer can be disposed only on the piezoelectric material and / or the conductive material forming the conductive lines and / or at least one electrode. The second layer may not be directly disposed on the substrate, or at least not directly on the side of the substrate opposite to the side of the substrate on which the piezoelectric material is disposed.

[0022] Methods may include applying a second layer by spin coating, vapor deposition, or other methods.

[0023] By incorporating a second layer, the frequency of vibration can be controlled, for example, based on the thickness of the second layer. For instance, the second layer can reduce the operating frequency of the piezoelectric device and / or suppress higher frequency vibrations (such as vibrations above 20 MHz), for example, to adapt the piezoelectric device to lower frequency operation (such as operation from 1 MHz to 20 MHz). Incorporating a second layer can reduce pinholes or other defects. Incorporating a second layer can lead to higher piezoelectric device yields and / or allow for larger electrode sizes. Incorporating a second layer can allow for high-voltage operation and can improve electrical durability. Incorporating a second layer can, for example, result in a lower failure rate due to bending and flexing, which can improve mechanical durability.

[0024] The substrate can be conductive, that is, it can be an electrical conductor. The substrate can be planar. The substrate can be a film or sheet. The substrate can be metallic, such as a metal film. The substrate can be or comprise metal or metal foil, such as aluminum foil.

[0025] The substrate may be an electrically grounding electrode, include an electrically grounding electrode, or be included in an electrically grounding electrode. The substrate may be a counter electrode of a working electrode, include a counter electrode of a working electrode, or be included in a counter electrode of a working electrode. The counter electrode or grounding electrode may form an electrode pair with at least one working electrode (e.g., the working electrodes of an electrode array), and this electrode pair may be disposed on the side of the piezoelectric material opposite to the counter electrode or grounding electrode. The surface of the substrate opposite the surface on which the piezoelectric material layer is disposed may be a radiating surface from which ultrasonic waves are radiated during use.

[0026] The substrate may be or include a thin foil. The substrate may have a thickness ranging from 20 μm to 200 μm. The substrate may be at least 6 times or 10 times or more thicker than the piezoelectric material layer.

[0027] The method may include removing selected portions of the piezoelectric material layer, for example, to expose a corresponding area on a substrate surface, on which the remaining portion of the piezoelectric material layer is disposed. The method may include using an acid such as hydrochloric acid or other suitable chemical agent to remove or etch selected portions of the piezoelectric material layer.

[0028] The method may include forming an electrical connection directly to the surface of the substrate on which the remaining portion of the piezoelectric material layer is disposed, for example, an electrical connection to a region of the substrate from which the piezoelectric material has been removed. The electrical connection may be to ground, such that the substrate is grounded via the connection, for example, such that the substrate acts as a ground electrode. Alternatively, a direct electrical connection to the substrate may not be formed except to the surface of the substrate on which the piezoelectric material is disposed.

[0029] In this way, all electrical connections to the piezoelectric device can be on the same side of the substrate and the resulting device, for example, on the side of the device opposite the radiating surface of the substrate. Furthermore, it is not necessary to fold the substrate to form a ground connection. This eliminates potential points of failure. There is also no damage or components located on the radiating surface; for example, electrodes or electrical connections may not exist on the radiating surface, ensuring that the radiating surface (equivalent to the effective surface of the piezoelectric device) is not damaged. This also increases durability.

[0030] Piezoelectric devices can be flexible. The substrate, piezoelectric material layer, at least one electrode, at least one conductive line, and / or at least one electrical connector can be flexible.

[0031] Advantageously, the ultrasonic transducers produced by the above method can provide continuously efficient acoustic output at high-temperature operation. This can be particularly beneficial in non-destructive testing applications. The flexibility of the resulting transducers allows them to be more easily conformed to desired shapes, which can be particularly beneficial in certain applications such as non-destructive testing. Furthermore, the resulting ultrasonic transducers can have high resolution, which can be particularly beneficial in certain applications such as medical and dental applications. A general benefit is that the above method can be used for scalable mass production at low cost.

[0032] According to one aspect of this disclosure, a piezoelectric device, such as an ultrasonic transducer or an array of ultrasonic transducers, is provided, the piezoelectric device comprising:

[0033] A piezoelectric material layer on a substrate.

[0034] Piezoelectric materials can be sputtered. The piezoelectric device can be formed using the method of the first aspect.

[0035] The piezoelectric material may be or includes doped or alloyed piezoelectric materials. The piezoelectric material may be or includes metal oxides or metal nitrides (such as zinc oxide or aluminum nitride) or doped or alloyed metal oxides or metal nitrides. The piezoelectric material and / or sputtering target may include dopants or other materials (e.g., alloying materials or co-deposited materials), which may be or include transition metals or compounds thereof. For example, the dopant or other material may be or include vanadium. The dopant or other material may be present in the piezoelectric material at a level of up to 10% w / w (e.g., 0.01% w / w to 10% w / w). The metal oxides or metal nitrides may be present in the piezoelectric material layer at a level of 90% w / w to 99.99% w / w. Dopants or other materials may be integrated or reacted into the piezoelectric material, for example, by forming an alloy with the piezoelectric material, co-depositing with it, or doping it into the piezoelectric material, and may not be mixed with the piezoelectric material or coated onto or within discrete regions within the piezoelectric material. An ultrasound device can be an ultrasound device used for imaging, measurement, or testing (e.g., non-destructive testing).

[0036] The piezoelectric material layer can be a piezoelectric material film, include a piezoelectric material film, or be included in a piezoelectric material film. The piezoelectric material layer can be configured and / or operable to generate ultrasound; that is, the piezoelectric material layer can be or include an ultrasound-generating layer. The piezoelectric material layer can be or include an inorganic material layer. The piezoelectric material layer can be or include a crystalline (e.g., polycrystalline and / or columnar piezoelectric material) layer. The piezoelectric material layer can be or include a non-polymeric piezoelectric material layer. The piezoelectric material can be or include a continuous layer of a material having piezoelectric properties; for example, the piezoelectric material may not be included in discrete regions of a piezoelectric material having piezoelectric properties within a non-piezoelectric material matrix. The piezoelectric material layer can have a thickness in the range of 2 μm to 20 μm. The piezoelectric material layer can be thinner than the substrate.

[0037] Piezoelectric devices, such as ultrasonic transducers or transducer arrays, may include at least one electrode on a piezoelectric material layer. Piezoelectric devices, such as ultrasonic transducers or transducer arrays, may include multiple electrodes in an electrode array on a piezoelectric material layer. Piezoelectric devices, such as ultrasonic transducers or transducer arrays, may include at least one conductive line and / or at least one electrical connector, for example, on the surface of the piezoelectric material or on a resistive layer disposed thereon. The corresponding conductive line can electrically connect the corresponding electrode to the corresponding electrical connector. However, other electrode and / or electrical connector arrangements and / or other methods for electrically coupling the piezoelectric material layer to an external system may be used.

[0038] The piezoelectric device may include a second layer. The second layer may include an encapsulation material. The second layer may be or include a dielectric material. The second layer may be or include a polymeric material, such as a dielectric polymer. The second layer may be thinner than the substrate. The thickness of the second layer may be less than 50 μm, for example, between 1 μm and 50 μm. The second layer may include epoxy resin, polyimide, parylene, etc., or be formed therefrom.

[0039] The second layer can be configured to be directly on, above, or covering at least a portion of the surface of the piezoelectric material layer. The second layer can be directly disposed on, above, or covering the side of the piezoelectric material layer opposite to the substrate. The second layer can be directly on, around, and / or between at least some or all of the conductive lines and / or at least one electrode (e.g., electrodes of an electrode array). The second layer can be electrically insulating. The second layer can expose at least some or all of the connector. The second layer can be disposed only on the piezoelectric material and / or the conductive material forming the conductive lines and / or at least one electrode, i.e., not on the substrate or at least not on the side of the substrate opposite to the side of the substrate on which the piezoelectric material is disposed.

[0040] The substrate can be conductive, that is, it can be an electrical conductor. The substrate can be planar. The substrate can be a film or sheet. The substrate can be metallic, such as a metal film. The substrate can be or comprise metal or metal foil, such as aluminum foil.

[0041] The substrate may be an electrically grounding electrode, include an electrically grounding electrode, or be included in an electrically grounding electrode. The substrate may be a counter electrode of a working electrode, include a counter electrode of a working electrode, or be included in a counter electrode of a working electrode. The counter electrode or grounding electrode may form an electrode pair with at least one working electrode (e.g., the working electrodes of an electrode array), and this electrode pair may be disposed on the side of the piezoelectric material opposite to the counter electrode or grounding electrode. The surface of the substrate opposite the surface on which the piezoelectric material layer is disposed may be a radiating surface from which ultrasonic waves are radiated during use.

[0042] The substrate may be or include a thin foil. The substrate may have a thickness ranging from 20 μm to 200 μm. The substrate may be at least 6 times or 10 times or more thicker than the piezoelectric material layer.

[0043] Selected portions of the piezoelectric material layer may be exposed; for example, a region of the substrate surface on which the remaining portion of the piezoelectric material layer is disposed may be exposed. The piezoelectric device may include an electrical connection directly to the substrate surface on which the remaining portion of the piezoelectric material layer is disposed, such as an electrical connection to an exposed region of the substrate. The electrical connection may be to ground, such that the substrate is grounded via the connection, for example, making the substrate act as a ground electrode. A direct electrical connection to the substrate may not be formed except for the surface on which the piezoelectric material is disposed.

[0044] Piezoelectric devices can be flexible. The substrate, piezoelectric material layer, at least one electrode, at least one conductive line, and / or at least one electrical connector can be flexible.

[0045] According to a third aspect of this disclosure, a set of computer-readable instructions or computer code is provided, which is configured to, when processed by manufacturing equipment, allow, control, or cause the manufacturing equipment to produce at least a portion of the piezoelectric device (e.g., an ultrasonic transducer or an array of ultrasonic transducers) of the second aspect or to perform at least some of the steps of the method of the first aspect, or to provide instructions or data for causing the manufacturing equipment to produce at least a portion of the piezoelectric device (e.g., an ultrasonic transducer or an array of ultrasonic transducers) of the second aspect or to perform at least some of the steps of the method of the first aspect.

[0046] The manufacturing equipment may be a sputtering system, include a sputtering system, or be included in a sputtering system. The manufacturing equipment may be computer-controlled or controllable.

[0047] This set of computer-readable instructions or computer code may be configured to, when processed by manufacturing equipment, allow, control, or cause additive manufacturing equipment to deposit a piezoelectric layer onto a substrate to at least partially form a device of the second aspect or perform a part of the method of the first aspect, or provide instructions or data for causing additive manufacturing equipment to deposit a piezoelectric layer onto a substrate to at least partially form a device of the second aspect or perform a part of the method of the first aspect.

[0048] According to a fourth aspect of this disclosure, an ultrasonic device configured to generate and emit ultrasonic waves is provided, the ultrasonic device including the piezoelectric element of the second aspect.

[0049] An ultrasonic device can be configured to receive reflections of emitted ultrasonic waves. The ultrasonic device can be used for imaging, measurement, or testing (e.g., non-destructive testing).

[0050] An ultrasound device can be a medical ultrasound imager. An ultrasound device can be a non-destructive testing device. An ultrasound device can be a dental ultrasound imager used for imaging structures or teeth.

[0051] According to a fifth aspect of this disclosure, a method for producing an ultrasonic transducer or an ultrasonic transducer array is provided, the method comprising:

[0052] A piezoelectric material layer is deposited on a substrate by sputtering, wherein the piezoelectric material is or includes doped, co-deposited or alloyed piezoelectric materials.

[0053] The sputtering deposition of the substrate can be performed using a sputtering deposition system with a sputtering target formed of or comprising a doped or alloyed piezoelectric material.

[0054] Methods may include using magnetron sputtering deposition, such as direct current (DC), pulsed DC, radio frequency (RF), closed field magnetron (CFM) sputtering, and / or high-power pulsed magnetron sputtering (HIPIMS), to deposit piezoelectric coatings. Further enhancements can be obtained using substrate bias (e.g., DC and / or RF), which can optimize sputtered plasma ion energy during film growth. These specific techniques can provide beneficial film growth morphologies and / or enhanced piezoelectric properties of the piezoelectric layer.

[0055] During the deposition of the piezoelectric material layer, dopants or other materials can be bonded to the primary piezoelectric material, such as a metal, metal oxide, or metal nitride. The dopants or other materials can be bonded within the sputtering target, for example, by doping into the primary piezoelectric material, such as a metal oxide or metal nitride, forming an alloy with it, or by co-deposition from multiple sputtering magnetrons. The dopants or other materials can be co-deposited with the primary piezoelectric material (e.g., a metal, metal oxide, or metal nitride). For example, the dopants or other materials can be provided by the target or sputtering arrangement, and the primary piezoelectric material (e.g., a metal, metal oxide, or metal nitride) can be provided by different targets or sputtering arrangements.

[0056] The fifth aspect of the method may also include any features or steps described above with respect to the first aspect.

[0057] According to a sixth aspect of this disclosure, an ultrasonic transducer or ultrasonic transducer array is provided, the ultrasonic transducer or ultrasonic transducer array including a piezoelectric material layer on a substrate, wherein the piezoelectric material is or includes doped, co-deposited or alloyed piezoelectric material.

[0058] The ultrasonic transducer or transducer array may also include any of the features described above with respect to the second aspect. The ultrasonic transducer or transducer array may be manufactured using the methods described in the fifth aspect.

[0059] According to a seventh aspect of the present invention, a method for producing an ultrasonic transducer or an ultrasonic transducer array is provided, the method comprising:

[0060] A piezoelectric material layer is disposed on the substrate; and

[0061] A second layer is provided, which is directly on, above, or covering at least a portion of the surface of the piezoelectric material layer, and / or directly on, above, or covering at least one conductive line and / or at least one electrode disposed on the piezoelectric material layer; wherein...

[0062] The second layer is or includes a layer of dielectric material such as a dielectric polymer.

[0063] The method may also include any features or steps described above with respect to the first aspect.

[0064] According to an eighth aspect of this disclosure, an ultrasonic transducer or ultrasonic transducer array is provided, comprising:

[0065] A piezoelectric material layer on a substrate; and

[0066] The second layer is directly on, above, or covering at least a portion of the surface of the piezoelectric material layer, and / or directly on, above, or covering at least one conductive line and / or at least one electrode disposed on the piezoelectric material layer; wherein...

[0067] The second layer is or includes a layer of dielectric material such as a dielectric polymer.

[0068] An ultrasonic transducer or transducer array may also include any of the features described above with respect to the second aspect.

[0069] According to a ninth aspect of the present invention, a method for producing an ultrasonic transducer or an ultrasonic transducer array is provided, the method comprising:

[0070] A piezoelectric material layer is disposed on the substrate; and

[0071] An electrical connection is formed directly to the surface of the substrate on which the remaining portion of the piezoelectric material layer is disposed.

[0072] The method may include removing selected portions of a piezoelectric material layer, for example, to expose a corresponding area on a substrate surface, on which the remaining portion of the piezoelectric material layer is disposed. The method may include removing or etching selected portions of the piezoelectric material layer using an acid such as hydrochloric acid or other suitable chemical agent. The method may include forming electrical connections directly to the exposed area of ​​the substrate from which the piezoelectric material has been removed.

[0073] The piezoelectric material layer may be disposed only on a portion of the substrate surface, for example, leaving an exposed portion of the substrate surface on which the piezoelectric material layer is disposed. The method may include forming an electrical connection directly to the exposed portion of the substrate surface on which the piezoelectric material layer is disposed.

[0074] The electrical connection can be a ground connection, allowing the substrate to operate as a ground electrode.

[0075] The method may also include any features or steps described above with respect to the first aspect.

[0076] According to a tenth aspect of this disclosure, an ultrasonic transducer or ultrasonic transducer array is provided, comprising:

[0077] A piezoelectric material layer disposed on a portion of the surface of the substrate; and

[0078] An electrical connection that is directly connected to another portion of the substrate surface that is not covered by the piezoelectric material layer.

[0079] The electrical connection can be a ground connection, allowing the substrate to operate as a ground electrode.

[0080] An ultrasonic transducer or transducer array may also include any of the features described above with respect to the second aspect.

[0081] According to a tenth aspect of this disclosure, a material, such as a piezoelectric material, is provided comprising a doped, co-deposited, molten, or alloyed metal compound, such as a metal oxide or metal nitride, which is doped, co-deposited, molten, or alloyed with a transition metal or a compound thereof. The metal oxide may be zinc oxide, such as ZnO. The metal nitride may be aluminum nitride, such as AlN. The transition metal or its compound may be or contain vanadium or a compound thereof. For example, the material may comprise a doped, co-deposited, molten, or alloyed metal oxide or metal nitride, and the metal oxide or metal nitride may be doped, co-deposited, molten, or alloyed with vanadium or a compound thereof. The material may be or comprise zinc oxide doped, co-deposited, molten, or alloyed with a transition metal or its compound. The material may be used or formed as a piezoelectric material in any of the methods or devices of the foregoing aspects.

[0082] Individual features and / or combinations of features defined above in any aspect of the invention or below with respect to any specific embodiment of the invention may be used individually and singly, independently or in combination with any other defined features in any other aspect or embodiment of the invention.

[0083] Furthermore, this invention aims to cover devices configured to perform any of the features described herein with respect to methods and / or methods for using, producing, or manufacturing any device features described herein. For any device feature described above as performing a function, this invention also covers methods that include performing that function. [Attached Image Description]

[0084] These and other aspects of this disclosure will now be described by way of example only with reference to the accompanying drawings, in which:

[0085] Figure 1 This is a flowchart illustrating a method for producing an ultrasonic transducer;

[0086] Figure 2 Figure 6 is Figure 1 A schematic diagram illustrating the steps of the method, wherein:

[0087] Figure 2 This is a schematic diagram illustrating the steps of depositing a piezoelectric layer onto a conductive planar substrate;

[0088] Figure 3 is a schematic diagram of the steps for adding electrodes, conductive lines, and connectors;

[0089] Figure 4 is a schematic diagram of the steps involved in etching away a portion of the piezoelectric material layer from the substrate;

[0090] Figure 5 is a schematic diagram showing the fixed grounding connection;

[0091] Figure 6 is a schematic diagram showing the arrangement of the dielectric layer;

[0092] Figure 7 It can be used Figure 1 A schematic plan view of an example ultrasonic transducer array produced by the method shown in Figure 6; and

[0093] Figure 8 yes Figure 7 A schematic side view of the transducer array.

Detailed Implementation Methods

[0094] Figure 1 Figure 6 shows the process for producing the ultrasonic transducer 5 (see Figure 6). Figure 7 and Figure 8 The process of ). Figure 1 A flowchart of the manufacturing process is shown. Figure 2 Figure 6 illustrates the steps in the manufacturing process. Figure 3A , Figure 4A , Figure 5A as well as Figure 6A A side sectional view of what will become part of the ultrasonic transducer 5 is shown, and Figure 3B , Figure 4B , Figure 5B as well as Figure 6B A floor plan is shown.

[0095] like Figure 1 As indicated in step 305 and as Figure 2 As shown, a substrate 10 in the form of a metal foil, such as aluminum foil, has a thin layer 15 of a polycrystalline piezoelectric material, such as a metal oxide doped with a transition metal, sputtered onto one side. In this example, the piezoelectric material is vanadium-doped zinc oxide (ZnO) or aluminum nitride (AlN), but other transition metal dopants or other metal salts exhibiting piezoelectric properties can be used. The thickness of the substrate can be from 20 μm to 200 μm. The thickness of the piezoelectric material layer 15 is approximately one-tenth the thickness of the substrate 10, for example, from 2 μm to 20 μm.

[0096] Advantageously, the piezoelectric material layer 15 is deposited onto the substrate 10 by sputtering. For example, the piezoelectric material 15 can be deposited using magnetron-based sputtering, such as closed-field magnetron sputtering or high-power pulsed magnetron sputtering, which can optimize the piezoelectric properties and / or growth morphology of the film.

[0097] exist Figure 2 In the example shown, high-power pulsed magnetron sputtering (HIPIMS) is used to coat the piezoelectric material 15 onto the substrate 10, but the invention is not limited thereto. Figure 2As shown, sputtering deposition is typically performed in a low-pressure chamber 405, which has an outlet 410 to a vacuum pump, an inlet 415 for allowing inert gas to enter, an electrode 420, a counter electrode 425 in the form of a drum, a target 430 electrically connected to the electrode 420, and a substrate 10 disposed on the surface of the counter electrode 425 on the drum. A grounded magnetron anode 431 is positioned close to the target 430. A pulsed high-voltage power supply (not shown) is connected to the electrode 420, which is coupled to the target 430.

[0098] A separate substrate bias power supply 432 is electrically connected to the drum electrode 425 and is operable to provide a DC or RF bias to the substrate 10. An electric field is generated to guide ionized sputtered material from the target 430 onto the substrate 10. The substrate bias can be varied or selected to attract ionized sputtered material from the target 430 to the substrate 10 to control the energy of the arriving ions. This allows for optimization of the sputtered plasma ion energy during film growth. The drum 425 is typically electrically floating, and the substrate bias from the substrate bias power supply 432 is applied via a rotating feedthrough / axis of the drum 425, thereby applying a voltage (bias) directly to the drum 425.

[0099] The target 430 is formed of a piezoelectric material doped with a transition metal, such as zinc oxide doped with vanadium. Importantly, the elements forming the piezoelectric layer are incorporated into the target, for example by alloying or doping, rather than being provided individually or discretely, for example, as a mixture or by adhering or otherwise setting the doped transition metal onto the surface of the metal oxide. In this way, the resulting piezoelectric layer 15 can have improved piezoelectric properties. Furthermore, the deposition rate can be increased, allowing for shorter deposition times and / or the growth of thicker piezoelectric layers within a given time. Additionally, fewer pinholes and other defects may occur.

[0100] The target 430 and the piezoelectric material layer 15 have an active piezoelectric material, such as a metal oxide or nitride, like ZnO or AlN, at a level of 90% w / w or higher (e.g., from 90% w / w to 99.99% w / w). Dopant / alloy materials, such as transition metals, are present in the target 420 and the piezoelectric material layer 15 at levels of 10% w / w and lower (e.g., from 0.01% w / w to 10% w / w).

[0101] A high voltage is provided between electrode 420 and counter electrode 425 to form a plasma in the chamber. Ions from the plasma are accelerated into target 430, from which doped piezoelectric material is sputtered, which is then deposited on the surface of substrate 10 via an adsorption process. As a result, one side of substrate 10 is coated with a piezoelectric material layer 15 doped with a transition metal.

[0102] In step 310 and as Figure 3A andFigure 3B As shown, a plurality of working electrodes 20 are disposed on the surface of the piezoelectric material layer 15 opposite to the substrate 10, and are respectively connected to the corresponding electrical connectors 30 via corresponding conductive lines 25. These working electrodes can be disposed using techniques such as photomask deposition, printing, selective patterning, etc.

[0103] In step 315 and as Figure 4A and Figure 4B As shown, a portion of the piezoelectric material layer 15 is removed to expose a corresponding portion of the surface of the substrate 10 on which the piezoelectric material layer 15 is disposed. This portion of the piezoelectric material 15 can be removed, for example, by selective etching using an acid such as hydrochloric acid.

[0104] As indicated in step 320 and as Figure 5A and Figure 5B As shown, the electrical grounding connection 17 is directly attached to the exposed portion of the surface of the substrate 10 on which the piezoelectric material layer 15 is disposed. In this way, all electrical connections of the substrate 10 (i.e., the grounding connection 17 and the connection to the piezoelectric material layer 15 and thus to the working electrode 20) are to the same surface of the substrate 10, and there are no connections directly formed to the opposite surface of the substrate (i.e., the radiating surface from which ultrasonic waves are radiated during use). Using this configuration, there is no need to fold material, which could otherwise provide potential points of failure. Furthermore, there is no damage or unwanted modification to the radiating surface of the substrate 10, ensuring that the radiating surface remains undamaged.

[0105] exist Figure 1 In step 325 and as Figure 6A and Figure 6B As shown, an electrically insulating dielectric material 35 is disposed above and around the outer surface of the piezoelectric material layer 15 (i.e., the surface opposite to the surface abutting the substrate 10), the electrodes 20, and the conductive lines 25 to protect and insulate them. The dielectric material 35 is also disposed between the electrodes 20 and between the conductive lines 25. The dielectric material 35 can be any suitable dielectric polymer material, such as epoxy resin, polyimide, parylene, etc. However, the contacts 30 and the ground connection 17 are exposed so that they can form the desired electrical connections.

[0106] The dielectric material 35 is typically thinner than the substrate, for example, with a thickness of 50 micrometers or less. The dielectric material 35 can be applied using suitable techniques known in the art, such as spin coating or vapor deposition.

[0107] The aforementioned dielectric material 35 provides advantages in the ultrasonic transducer array 5. For example, it can reduce the operating frequency or suppress high-frequency vibrations (e.g., vibrations greater than 20 MHz), which is particularly beneficial in low-frequency applications (e.g., in the range of 1 MHz to 20 MHz). Furthermore, the electrical insulation provided by the dielectric material reduces pinholes and other defect failures. The dielectric material can also help the transducer array 5 withstand higher voltage pulses and improve electrical durability. It can also improve mechanical durability and reduce failures due to bending and deflection.

[0108] Figure 7 A schematic plan view of an exemplary ultrasonic transducer array 5, which can be produced using the methods of claims 1 to 6, is shown. Figure 8 A schematic side view of the ultrasonic transducer array 5 is shown. Figure 7 and Figure 8 The ultrasonic transducer 5 shown is provided only as an example of its usability. Figure 1 The method shown in Figure 6 is an example of an ultrasonic transducer produced by the method, and the method can also be applied to the production of other ultrasonic transducers and transducer arrays.

[0109] An exemplary ultrasonic transducer array 5 includes a conductive substrate 10 in the form of a metal foil (aluminum foil in this case) and a crystalline piezoelectric material layer 15 disposed on a flat surface of the substrate 10. The substrate 10 serves to support the piezoelectric material layer 15 and also acts as a ground electrode. The surface of the substrate 10 opposite to the surface on which the piezoelectric material layer is disposed serves as an ultrasonic radiating surface from which ultrasonic waves are emitted from the transducer array during use. A portion of the surface of the substrate 10 in contact with the piezoelectric material layer 15 does not contain piezoelectric material but is instead provided with an electrical ground connection 17.

[0110] The substrate 10 is significantly thicker than the piezoelectric material layer 15 (i.e., on the order of 10 times thicker), and in this example, the thickness of the substrate 10 is between 20 μm and 200 μm, while the thickness of the piezoelectric material layer 15 is between 2 μm and 20 μm. In this example, the piezoelectric material is vanadium-doped ZnO; however, it should be understood that other suitable piezoelectric materials, such as AlN and / or other dopants, particularly other transition metal dopants, can be used.

[0111] One or more working electrodes 20 are disposed on the surface of the piezoelectric material layer 15 on the side of the piezoelectric material layer 15 opposite to the substrate 10. Each working electrode 20 is connected to a corresponding conductive line 25, which in turn is electrically connected to an associated electrical connector 30.

[0112] An electrically insulating dielectric polymer material layer 35 is disposed on the piezoelectric material layer, and above and between the electrode 20 and the conductive line 25. Examples of suitable electrically insulating dielectric polymer materials 35 include epoxy resin, polyimide, parylene, etc. However, the connection between the connector 30 and the substrate 10 to electrical ground is exposed to allow for electrical connections to a controller or processing device. The radiating surface of the substrate 10 (i.e., the surface of the substrate opposite the piezoelectric material 15) is also exposed and without encapsulation material. The thickness of the dielectric material layer 35 ranges from 1 micrometer to 50 micrometers.

[0113] To generate ultrasound, an alternating current driving current is applied to one or more suitable connectors 30, thereby applying it via conductive lines 25 to one or more corresponding working electrodes 20. The working electrodes 20 are coupled (by means of grounding connection 17) to a conductive substrate 10 acting as a ground electrode, so as to apply alternating current to corresponding portions of the piezoelectric material 15. This, in turn, causes the corresponding portions of the piezoelectric material layer 15 to vibrate together with the corresponding portions of the substrate 10 at a high frequency, thereby generating ultrasound waves emitted from the portions of the outer surface of the substrate 10 corresponding to the driven one or more working electrodes 20.

[0114] Although specific examples have been described above with reference to the accompanying drawings, it should be understood that modifications to these examples are possible. Therefore, the scope of protection is defined by the claims, not by the specific examples described above.

[0115] For example, although examples of piezoelectric materials as ZnO or AlN are given above, it should be understood that other piezoelectric materials can be used alternatively. Furthermore, although piezoelectric materials doped with transition metals are described, it should be understood that undoped piezoelectric materials can be used. Additionally, although various thicknesses, sizes, numbers, and geometric arrangements of electrodes, conductive lines, and contacts are given above, it should be understood that other thicknesses, sizes, numbers, and geometric arrangements of electrodes, conductive lines, and contacts can be used. In practice, although the electrodes are all shown as having the same dimensions and shape, it should be understood that at least some or all of the electrodes can have different dimensions and / or shapes. Although various specific examples of dielectric materials are given, other suitable dielectrics can be used. Although specific examples of etchants are used, other suitable etchants can be used alternatively.

[0116] Furthermore, while the examples given above advantageously use doped, alloyed, or amalgam targets to sputter-deposit metal oxides or metal nitrides doped with transition metals, it should be understood that other methods can be used to produce suitable monolithic transition metal / metal oxide or metal nitride piezoelectrics. For example, transition metals and metal oxides or metal nitrides can be co-deposited from a dual-source system.

[0117] Additionally, although substrate 10 is in Figure 2 The image is shown on a rotating drum as the piezoelectric layer 15 is deposited onto the substrate 10, but it should be understood that the substrate 10 may be disposed on a flat, stationary surface.

Claims

1. A method for producing a flexible ultrasonic transducer or ultrasonic transducer array for imaging, measurement, or nondestructive testing, the method comprising: A piezoelectric material layer is disposed or deposited on a substrate including a metal foil; wherein, The piezoelectric material layer has a thickness in the range of 2 μm to 20 μm, and the substrate has a thickness in the range of 20 μm to 200 μm; The piezoelectric material is a doped, co-deposited, or alloyed piezoelectric material; and The piezoelectric material includes: Doped, co-deposited, or alloyed metal oxides or metal nitrides, wherein the metal oxides or metal nitrides are doped, co-deposited, or alloyed with vanadium or its compounds; or Zinc oxide that is doped, co-deposited, or alloyed with transition metals or their compounds.

2. The method according to claim 1, wherein, The piezoelectric material layer is deposited by sputtering a sputtering target that includes doped or alloyed materials.

3. The method according to claim 1, wherein, The doped, co-deposited, or alloyed piezoelectric material comprises a primary piezoelectric material and a dopant or additional material, wherein the dopant or additional material is present in the piezoelectric material at a level of 0.01% to 10%, and the primary piezoelectric material is present in the piezoelectric material layer at a level of 90% to 99.99%.

4. The method according to claim 2, wherein, The sputtering coating includes the use of DC, pulsed DC, RF, closed field magnetron (CFM) sputtering, high power pulsed magnetron sputtering (HIPIMS) or other magnetron sputtering methods.

5. The method according to claim 3, wherein, The dopant or other material is co-deposited with the primary piezoelectric material, wherein the dopant or other material is provided by a target or sputtering arrangement, and the primary piezoelectric material is provided by a different target or sputtering arrangement.

6. The method according to claim 1, wherein, The substrate is disposed on a rotating drum or linearly moving plate when the piezoelectric material layer is deposited onto the substrate.

7. The method according to claim 1, wherein, The piezoelectric material layer is an ultrasonic generating layer, which is configured and / or operable to generate ultrasound for imaging, measurement, or non-destructive testing.

8. The method according to claim 1, wherein, The piezoelectric material layer is an inorganic, crystalline, columnar, non-polymerized piezoelectric material layer.

9. The method according to claim 8, wherein, The inorganic, crystalline, columnar, non-polymeric piezoelectric material is polycrystalline.

10. The method of claim 1, further comprising a second layer comprising an electrically insulating dielectric material directly on, above, or covering at least a portion of the piezoelectric material layer.

11. The method according to claim 10, wherein, The thickness of the second layer is less than 50 μm.

12. The method according to claim 1, wherein, The substrate is an electrical conductor and forms the electrical grounding electrode of the flexible ultrasonic transducer or ultrasonic transducer array used for imaging, measurement, or non-destructive testing.

13. The method according to claim 1, wherein, The method includes removing a selected portion of the piezoelectric material layer to expose a corresponding area on the surface of the substrate, with the remaining portion of the piezoelectric material layer disposed on that corresponding area.

14. The method of claim 13, further comprising removing or etching selected portions of the piezoelectric material layer using an acid or other suitable chemical agent.

15. The method of claim 1, further comprising forming an electrical connection directly to the surface of the substrate on which the piezoelectric material layer is disposed.

16. The method according to claim 15, wherein, The method includes: removing a selected portion of the piezoelectric material layer to expose a corresponding area on the surface of the substrate, with the remaining portion of the piezoelectric material layer disposed on the corresponding area, and forming an electrical connection directly to the corresponding area on the surface of the substrate.

17. The method according to claim 15, wherein, The electrical connection is a grounding connection.

18. A set of computer-readable instructions or processing protocols or computer code configured to, when processed by a manufacturing apparatus, permit, control, or cause the manufacturing apparatus to perform the method of claim 1, or provide instructions or data for causing the manufacturing apparatus to perform the method of claim 1.

19. The computer-readable instructions or computer code according to claim 18, wherein, The manufacturing equipment is a computer-controlled sputtering system, includes the sputtering system, or is included in the sputtering system.

20. An ultrasonic transducer for imaging, measurement, or nondestructive testing, the transducer comprising: A flexible piezoelectric material layer on a flexible substrate including a metal foil, wherein: The piezoelectric material layer has a thickness in the range of 2 μm to 20 μm, and the substrate has a thickness in the range of 20 μm to 200 μm; The piezoelectric material is a doped, co-deposited, or alloyed piezoelectric material; and The piezoelectric material includes: Doped, co-deposited, or alloyed metal oxides or metal nitrides, wherein the metal oxides or metal nitrides are doped, co-deposited, or alloyed with vanadium or its compounds; or Zinc oxide that is doped, co-deposited, or alloyed with transition metals or their compounds.

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